THE FOSSIL CRINOID GENUS DOLATOCRINUS AND ITS ALLIES. 19' 



Rowley; in Greexe. Contribution to Indiana Paleontology, vol. 1; issued in 20 

 parts, Feb., 1898. to Sept., 1904, continuously paged, pp. 1-204, plates 1-60; and 

 three parts of vol. 2, July, 1906, to Nov., 1906, pp. 1-38, plates 1-9. Cited : " Rowlej^ 

 in Greene, 1903, etc." 



The genus Dolatocrinus is remarkable among all Camerata for the- 

 extraordinary number of species which have been described under 

 it from a single horizon within a small local area. The total number 

 of named species and varieties for all areas is 77, all from the Middle- 

 Devonian, of which 15 are from the Onondaga and 62 from the 

 Hamilton. Sixty-five belong to the Louisville area, and of these^ 

 49 species and 4 varieties are described from the Hamilton alone. 

 The crinoid-producing exposures in the Hamilton beds of this area 

 are of very limited extent, being confined principally to a few miles 

 opposite Louisville, and along Silver Creek and other streams in 

 Clark County, Indiana, from which the types of nearly all the 53 

 alleged species and varieties have been derived. The specimens are 

 almost never found ^^■ith any part of the arms attached, and we 

 know nothing of the structures distal to the cah'x, except that the 

 arms are biserial and probably always simple. Hence the descrip- 

 tions are necessarily restricted to characters observed in the calyx 

 alone, which in this genus is of the most simple construction, having 

 a nearly pentamerous symmetry, so that we are without the benefit 

 of characters for discrimination usually afforded by the presence of 

 anal structures. The slight differences occasionally noticed in the 

 second or third ranges of interradial plates are inconstant and mostl}' 

 sporadic. 



The occurrence of such an incredible number of species of one 

 genus, from a single horizon at the same locality, is in the highest 

 degree improbable; and the statement of the foregoing facts alone 

 is sufficient to put the list under suspicion. It is of importance that 

 the character of the crinoidal fauna of this celebrated locality should 

 be correctly understood, in order that authors and students may not 

 bo misled into erroneous conclusions regarding it. 



The greater part of this multiplication of specific names is due 

 to the activities of Miller and Gurley, who, during the years 1894-1897, 

 published in the Bulletins of the Illinois State Museum 37 species of 

 Dolnfocrinus from the Hamilton beds alone, in addition to four from 

 the underlying Onondaga, all from the vicinity of Louisville. By 

 the work of these authors, chiefly in the publications mentioned, 

 and of Mr. ^Miller alone in the reports of the Geological Surveys of 

 Missouri and Indiana, several hundred species of crinoids and blas- 

 toids were described and illustrated, mainly from specimens in the 

 rich collection accumulated by Mr. Gurley, which he afterwards 

 placed at the service of science by donating it to the Walker Museum 

 of the Universitv of Chicago. Bv these means a great number of 



